Havamal

With insult or derision treat thou never a guest or wayfarer, they often little know, who sit within, or what race they are who come.

Ráðumk þér Loddfáfnir en þú ráð nemir njóta mundu ef þú nemr þér munu góð ef þú getr at háði né hlátri hafðu aldregi gest né ganganda

Havamal: 132, Loddfáfnismál